Networking Platform ICS

Hi everyone, I have this problem that i need to get sorted. I have a T-Mobile 3G internet dongle, what i am trying to do is Share the Internet from the dongle to my home networked computers, 3 Laptops 2 Desktops and Server. I say server because this is where all my machines get backed-up to, and also where i would like to have the connection shared from.

So i asking you now,

1.Do you think that this is even possible?
2.Whats the Best Platform (OS) to do this on?
3.All the Computers run a mix of Operating system.

Windows XP (on two Laptops)
Windows 7 (on Both Desktops)
Mac os X (this can GO PERMANENT if it has to!) (laptop)
Server Running Windows XP

But i run windows for the most part, can this be done from windows or OS X, Currently i have had no look with OS X or Windows 7.


My Network is Configured Like So.
Router Is Set with DHCP Disabled for LAN.
The two Desktops are Linked to the router Via 10MBPs Lan cable (not crossover)
All the laptops are on Wifi 54MBPS
SERVER is link Via 10MBPs LAN Cable

Right so thats that!

IP ranges Are from 192.168.1.60 To 192.168.1.100 (static)
Router IP 192.168.1.254 (Alway Been the same)

I have the DNS of the dongle and it installs the dongle as DIAL Up connection.


i think that all the info i can come up with to help you out, please help it doing my head now ha ha

Thanks

Graham